JPS62136899A - Inspecting apparatus of soldered parts - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a soldering inspection device for inspecting the quality of soldering of terminals of circuit elements attached to a printed circuit board.

[Prior Art] Conventionally, the dip method has been used to solder circuit elements on printed circuit boards, in which the board is immersed in molten solder in a dip bath.
Due to the miniaturization of circuit elements on printed circuit boards, soldering defects called bridges are increasing in this dip method.

This bridge defect is a short-circuit between adjacent ends R due to solder, and the shape of the bridge is larger than that of regular soldering, with the short-circuited part being larger than normal soldering. ]. Such a bridge is clearly a circuit failure and must be inspected, extracted, and removed.

As an inspection device for inspecting the quality of soldering, in addition to the above-mentioned bridges, an inspection device called a fluorescence detection method that uses laser light is being developed to detect various defects including disconnections. It is expensive. On the other hand, most soldering defects caused by the dip method are
Since the current situation is that bridges are the most common, there is great value in the existence of a simple and high-performance inspection device for detecting bridges, and the development of such a device is desired.

[Objective of the Invention] In view of the above, an object of the present invention is to provide a simple soldering inspection device that optically detects bridges that occur during soldering using a dip method.

[Means for Solving Problems] and [Operations] In this invention, we focused on the fact that in the bridge part, +I', the solder is raised 1 unit higher than in the current soldering. , which is detected by an optical and simple method. That is, one target is to detect the unevenness of the soldering joint, and the following optical system is used for this purpose.

The real image of the point light source formed by the light projection lens &mi is focused near the surface to be inspected, and the light projection lens is vibrated in the front and rear directions. Naturally, the real image at the focal point also vibrates, but when the focal point just matches the surface to be inspected, the intensity of the reflected light from the surface to be inspected reaches its maximum. Therefore, such a real image,
In other words, if you scan the surface to be inspected while vibrating the light spot and know both the vibration position of the lens where the reflected light has the maximum intensity and the scanning position, you can easily detect the unevenness of the surface to be inspected in two dimensions. It is something that can be detected.

FIG. 1(a) explains the stage of detecting unevenness on the surface of an object by vibration of a light spot according to the present invention. , the light spot oscillates between p and m, with the light spot centered at S' and p'.

It vibrates between m゛. 1- As mentioned above, the intensity of reflected light at the surface of object l is maximum when the focus of the light spot coincides with the surface.

Therefore, the lens 2 is moved in the direction of arrow B to scan the surface of the object 1. Corresponding to the horizontal axis in FIG. 1(a), as shown in FIG. 1(b), the position of the lens 2 showing the maximum intensity at each scanning position is known between p#-m''. If possible, the waveform 1'' connecting these points will represent the shape of the surface of the object 1 in a similar manner. The position of the lens 2 at which the reflected light has the maximum intensity can be determined by the configuration of the optical system and circuit, as well as signal processing technology, and will be explained in the following examples.

[Example 2] Fig. 2 shows the configuration of a soldering inspection device according to the present invention, in which a circuit element J'-4 is attached to a printed circuit board 3 to be tested, and the end r is connected to the dip type on the back side of the board. As a result, soldering is performed and a soldered portion 6 is formed. Here, the part shown at 6' is a bridge, and adjacent terminals are short-circuited with solder.

In the detection head 7, light from a point light source 8 passes through a half mirror 9, is focused by a lens 2, and illuminates a printed circuit board 3. On the other hand, the current from the lens drive circuit 11 causes the lens 2 to vibrate together with the coil 10. Printed circuit board 3
The reflected light is more diffused than when it is projected, but the part near the optical axis and focused on the lens 2 travels to the right by the half mirror 9, passes through the pinhole 12, and enters the photoelectric element 7. −
13. Here, the pinhole 12 is at the same distance as the point light source 8 with respect to the half mirror 9, and if the substrate 3.
When the reflecting surface coincides with the focal point of the projected light spot, the image of the received light beam has a minimum diameter and its position coincides with the pinhole 12. At this time, the light received by the photoelement f'13 [11] is maximum. On the other hand, if the reflective surface is shifted, the light receiving spot at the pinhole will expand, the amount of light blocked by the pinhole 12 will increase, and the light reception will be reduced. In this way, due to the pinhole effect, the light received by the photoelectric element 13 1d is approximately proportional to the intensity of the reflected light.

Next, the electronic circuit shown in FIG. 2 will be described. Charging element 13
From the waveform of the signal obtained in , the peak detection circuit 14 detects the time of the peak value, and based on this and the phase of the drive current of the lens drive circuit 11, the shape recognition circuit 15
Information about the unevenness of the reflective surface can be changed. In addition, the detection head drive unit 17 operates according to the command from the microcomputer 16, causes the detection head 7 to scan, and passes information on the scanning position to the shape recognition circuit 15, which converts data on the two-dimensional surface shape. It will be done. In this case, data on the three-dimensional shape can be changed by performing a surface scan of the surface to be inspected, but in order to detect bridges on a printed circuit board, it is necessary to scan the entire surface. By performing line-like scanning along the array, it takes -1- minutes.

On the other hand, in the microcomputer 16, page 1 [
：, shi<, A device that stores the data of the unevenness of the printed circuit board being soldered and compares it with the data obtained by the detection described in ``-'' to detect the presence or absence of bridges, thereby determining the quality of the soldering. It is.

The signal and data processing techniques described above are conventional and will not be described in detail.

[Effects of the Invention] As is clear from the following explanation, the soldering inspection device according to the present invention reliably detects bridges that occur during soldering of printed circuit boards by the dip method. Both equipment configurations are simple, so
It is highly practical and will greatly contribute to the production technology of printed circuit boards.

[Brief explanation of drawings]

FIG. 1(a) and FIG. 1(b) are diagrams explaining the principle of an optical method for detecting the shape of an object surface according to the present invention;
FIG. 2 is a block diagram of an embodiment of the soldering inspection apparatus according to the present invention. 1...Object, 2...Lens, 3...
・Print, (board, 4... circuit element, 5...
End r1 6...Soldering part, 6.00
．． Bridge, 7...Detection head) 8...Point light source, 9...Half mirror-1IO...
Coil, 11... Lens drive circuit, 12... Pinhole, 13... Photoelectric J7-114... Peak detection circuit, 15... Shape recognition circuit, 1B... Microcomputer, I7. ...Detection head drive unit.

Claims (1)

[Claims] (1) A point light source that emits light onto the surface of the soldered part of the printed circuit board, a vibrating lens that vibrates in the optical axis direction, and a pinhole that receives reflected light from the surface of the soldered part via the vibrating lens. According to the vibration position of the vibrating lens at which the light reception signal obtained by the light reception shows a peak value, and the scanning position of the detection head,
A soldering inspection device characterized by having a shape recognition circuit that recognizes the shape of the surface of the object.